The present invention relates to Braille and graphic displays for providing individuals with visual impairments a means to access media through the use of tactile devices.
Prior art in the field of Braille displays for computer interfaces utilize various mechanisms to actuate the Braille dots and refresh the text. Actuators known in the art comprised of piezoelectric materials, shape memory alloys and solenoids control the Braille dots. These actuators serve to raise and lower the individual pins to represent the Braille characters. The Braille cell displays utilizing these actuator technologies are limited to the display of one or two lines. The size and complexity of the actuators and the tight tolerance requirements for the Braille dots limits the number of Braille characters that can be presented simultaneously. These Braille cell devices known in the art also exhibit high power requirements, slow refresh rates and complex manufacturing processes.
Due to the limitations inherent in the Braille cells available to construct Braille cell displays, current technology provides for Braille displays that are limited to a few lines as displayed on a computer screen at one point in time. It is advantageous to be able to provide a reader with a full-page Braille display representing an entire screen. The fabrication of a full-page Braille display will allow the reader to access both character and graphic information.
Electroactive polymers are known in the art. These polymers respond to external electrical stimulation by displaying a significant shape or size displacement. Electroactive polymers have the ability to induce strains that are as high as two orders of magnitude greater than the movements possible with rigid and fragile electroactive ceramics, such as piezoelectric materials. Electroactive polymers inherently exhibit quicker response times, lower densities and improved resilience when compared to shape memory alloys. Two major categories of electroactive polymers are identifiable based on their driving mechanism. Electronic electroactive polymers are driven by the Coulomb forces resulting from the electric field applied, while ionic electroactive polymers are driven by the mobility or diffusion of ions.
A need exists for a refreshable Braille display that overcomes the prior art limitations by providing a tactile array that can give readers access to full computer generated screens of text and graphical information in real time. Accordingly, an improved Braille cell is needed that will allow the construction of a full Braille cell display. The Braille cell needs to have a quick response time, be compact in size, operate under low power, and be lightweight while still providing the necessary tactile response to the reader.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified need could be fulfilled.